Forward looking sonic wellbore inspector

ABSTRACT

A forward looking sonic wellbore inspector comprising a segmented acoustic transceiver utilizing oriented piezoelectric crystals to produce seismic energy which is reflected by a fish lost within the wellbore. Reflected energy waves from the fish are received by the piezoelectric crystals, the associated stress generates a voltage which is received by a transducer segmented scanner amplified and filtered into a signal utilized in conjunction with an orientation device and depth indicator to locate the fish and project a visual display at the earth&#39;&#39;s surface of the exact orientation of the fish in the wellbore.

8 L o ilmte Mates atent 1 1 3,735,338 Aidrich et ai. 1 May 22, 1973 [541 FORWARD LOOKING SONIC 3,503,038 3/1970 Baldwin ..a4o/1a R WELLBORE WSPECTOR 3,560,915 2/1971 Elliott et al. ..340/18 R [75] Inventors: g :52 Karl Land Primary Examiner-Benjamin A. Borchelt Assistant Examiner-G. E. Montone [73] Assignee: Cities Service Oil Company, Tulsa, Attomey-J. Richard Geaman Okla.

221 Filed: July so, 1971 [57] ABSTRACT [21] Appl No: 167,720 forward looking sonic wellbore inspect or comprismg a segmented acoustic transceiver utilizing oriented piezoelectric crystals to produce seismic energy which [52] US. Cl. ..340/l8 R, 181 /O.5 R i reflected by a fish lost within the wellbore. [51 Hnt. Cll. ..G0lv 1/00 R fl ted energy waves from the fish are received by [58] Field 05 Search ..340/18 R; 181/05 R; th i zoelectric crystals, the associated stress 166/2553 l75/45 generates a voltage which is received by a transducer segmented scanner amplified and filtered into a signal References CM utilized in conjunction with an orientation device and depth indicator to locate the fish and project a visual UNITED STATES PATENTS display at the earths surface of the exact orientation 3,637,038 l/l972 Tanner l8l[0.5 R of the fish in the wellbore. 3,275,096 3,502,169 3/1970 Chapman ..340/l8 R 8 Claims, 3 Drawing Figures PATENTEU 3 735.338

SHEET 1 BF 2 I w M I05 KARL M. LAND, CHARLES A. ALDRICH,

INVENTORS.

ATTORNEY.

PATEN {Eb MY 2 2 I975 SHEET 2 OF 2 fin: 2

KARL M. LAND, CHARLES A. ALDRICH,

INVENTORS, ayww ATTORNEY.

FORWARD LOOKING SONIC WELLBORE INSPECTOR BACKGROUND OF THE INVENTION The present invention relates to an apparatus for forward looking sonic wellbore inspection. More particularly, the apparatus of the present invention comprises a means for utilizing piezoelectric crystals in a forward looking sonic wellbore inspector.

The presence of undesirable objects in wellbores resulting from sticking or severing of drill pipe, bit breakage, tubing failures, separation of wire lines while running logs or other wire line tools, and a myriad of other causes, is a frequently occurring situation during the drilling, completion or workover operations of hydrocarbon producing wells. Retrieving such debris to the surface is costly both economically and in time consumption. Inability to clear the wellbore of objects may result in complete loss of a well.

Various and sundry means for retrieval of objects obstructing wellbores have been proposed. Retrieval and fishing operations are hampered by the unknown conditions and configurations of debris found in wellbores. Impression tools, which employ soft, pliable materials to obtain an impression of the uppermost part of the wellbore and debris, are used in attempting to ascertain these unknowns. Such tools are cumbersome, as they require tripping with the drill pipe or tubing. The retrieval apparatus are generally run blind" in the wellbore and are unreliable. What is required is a means to facilitate the removal of objects obstructing wellbores, while additionally provide information for research and other operations, but not requiring the tripping of drill pipe or production tubing, so as to eliminate the conventional limitations placed upon retrieval apparatus.

It is an object of the present invention to provide an apparatus for forward looking sonic wellbore inspection.

It is a further object of the present invention to provide a forward looking sonic wellbore inspector which may be utilized as a wire line tool in a wellbore having drill pipe or production tubing therein.

It is still a further object of the present invention to provide a forward looking sonic wellbore inspector which utilizes piezoelectric crystals for generation of sonic waves and the retrieval of reflected seismic waves in order to project an imagery of a fish contained within a blocked wellbore.

With these and other objects in mind, the present invention may be more fully understood by referral to the accompanying drawings and the following description:

SUMMARY OF THE INVENTION The objects of the present invention are accomplished through use of a forward looking wire line sonic wellbore inspector. The apparatus comprises a housing having a segmented piezoelectric crystal acoustic transceiver positioned in the lower portion of the housing. Means for imparting energy to the piezoelectric crystals and means for receiving and interpreting the reflected sonic energy received by the piezoelectric crystals are also provided. The apparatus may further comprise means for determining the orientation of the housing in the wellbore in conjunction with means for determining the depth of the housing in the wellbore. Additionally, means for visually displaying the difference between the imparted energy and reflected sonic energy received by the piezoelectric crystals and their correct orientation may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be more fully understood by referral to the accompanying Figures in which;

FIG. 1 represents one embodiment of a forward looking sonic wellbore inspector of the present invention with its orientation in a wellbore as utilized in determining the positioning of a fish;

FIG. 2 represents a segmented acoustic transceiver comprising piezoelectric crystals forming the transceiver located within the lower portion of the housing of the forward looking wire line sonic wellbore inspector; and

FIG. 3 represents a piezoelectric element and its orientation within an electromechanical insulator as used to isolate the anisotropic transceiver segments within the segmented acoustic transceiver of the forward looking wire line sonic wellbore inspector of the present invention.

DETAILED DESCRIPTION OF THE INVENTION In general, the forward looking sonic wellbore inspector of the present invention is a wire line tool which may be introduced within a wellbore containing drill pipe or tubing such that a drilling operation or production interval need not be ceased other than during the inspection of the wellbore with a wire line sonic wellbore inspector. Generally, the apparatus of the present invention comprises a housing, preferably being circular in shape so that it conveniently can be passed within tubing or drill pipe contained within wellbores or within the wellbore itself. The housing has a segmented piezoelectric crystal acoustic transceiver positioned in the lower portion thereof with means for imparting energy to the piezoelectric crystals and means for receiving and interpreting the reflected sonic energy from the piezoelectric crystals. To further complement the forward looking wellbore inspector of the present invention, means for determining the orientation of the housing in the wellbore and means for determining the depth of the housing in the wellbores are provided. Electronic signals from the orientation and depth determining means and from the means for interpreting the reflected sonic energy received and generated by the piezoelectric crystals may be visually displayed in a correct orientation in order to physically represent a picture of the orientation and geometry of the wellbore obstruction or fish.

The apparatus of the present invention may be more readily understood by referral to the accompanying FIG. 1 in which a preferred embodiment of the forward looking sonic wellbore inspector of the present invention is depicted. The forward looking sonic wellbore inspector comprises a housing 101, having a segmented piezoelectric crystal acoustic transceiver 106 positioned in the lower portion thereof. The housing 101 is depicted as lowered into a wellbore 103 full of fluid, which has been drilled into formation 104. The wellbore 103 has a lost joint of pipe or fish 105 contained therein of which it is the objective of the forward looking sonic wellbore inspector to determine the orientation and positioning thereof. In FIG. 1, the segmented piezoelectric crystal acoustic transceiver 106 has a protective skirt 107 on the acoustic transceiver face. The housing 101 is orientated within the wellbore 103 by one or more bowstring centralizers 141 contained on the housing 101 so as to depress against the formation 104 within the wellbore 103 and thereby exactly position the housing 101. The apparatus further comprises means for determining the orientation of the housing in the wellbore which may be provided by a flux-gate magnetometer 142, utilized to determine the azimuth or orientation of the housing 101 within the wellbore 103 through generation of a signal 122 from an orientation pulse generator-receiver 123. The signal 122 is pulsed to the flux-gate magnetometer 142 which thereby generates a signal 122 therefrom which is received by the orientation pulse generator-receiver 123 and subsequently produced as orientation signal 124. Means for determining the depth of the housing in the wellbore are also provided which may comprise the wire line 102, connected to the housing 101 for lowering the wire line sonic wellbore inspector within the wellbore 103, passing over a depth indicator pulley 125 connected to a depth potentiometer 126 which generates a depth signal 127.

In general, the forward looking wire line sonic wellbore inspector operates through means for imparting energy to the piezoelectric crystals. These means may comprise a frequency generator 108 generating a frequency signal 115 to a pulse generator 109 and a fre quency signal 114 to a transducer segment scanner 110. The pulse generator 109 receives the frequency signal 115 and gives off a pulse frequency signal 116. The transducer segment scanner 110 receives the frequency signal 1 14 and pulse frequency signal 116. The transducer segment scanner 110 is electrically connected to the piezoelectric crystals so as to give off a pulse frequency signal 143 which is received by the piezoelectric crystals contained within the segmented acoustic transceiver 106 and transformed into an acouslic wave 144 which is projected downwardly through the wellbore fluid in the wellbore 103 so as to interscept and be reflected by the fish 105. Returned acoustic waves are received by the segmented acoustic transceiver 106 as reflected sonic energy 145. The reflected seismic energy 145 received by the segmented acoustic transceiver 106 is transformed into a voltage signal 143, which is transmitted to the transducer segment scanner 110. A gate trigger 111 is utilized in order to receive reflected sonic energy 143 through transducer segment scanner 1 with the frequency energy 114, from the frequency generator 108, as signal 117. The gate trigger 111 returns a signal 118 to the transducer segment scanner 110. An alternating frequency signal and reflected sonic energy signal 119 is received by first amplifier 112 from the gate trigger 111. The amplified signal 120 is relayed to a counter detector 113 which filters the energy from the frequency-energy and reflected sonic energy so as to determine the energy difference received from the piezoelectric crystals and imparted to the piezoelectric crystals. This difference is generated as a signal 121.

Means for visually displaying the difierence between the imparted energy and reflected sonic energy received by the piezoelectric crystals as formed into signal 121, along with the orientation signal 124 and depth signal 127 may be utilized. These means for visually displaying the signals may comprise a second amplifier 147 receiving the difference signal 121 through the wire line 102 as signal 146 into the second amplifier 147, with the amplified difference signal 148 being fed to the Z-axis coordinate 149 of an oscilloscope 140. The difference signal 121 is also fed through the wire line 102 as difierence signal 128 which is received by transducer-scanner 129, with the transducer-signal 130 fed to the horizontal 131 and vertical 132 circuitry of the oscilloscope 140. The orientation signal 124 is fed through the wire line 102 and received as an orientation signal 133 into an aximuth marker 134, with an azimuth marker signal 135 being received as an aximuth mark 136 on the oscilloscope 140. The depth indication signal 127 is received by a numerical counter 138 so as to visually display numerically the depth of the forward looking sonic wellbore inspector in the wellbore 103. Therefore, a visual display 137 of the fish 105 may be shown on the oscilloscope 140 at the surface, such that means for permanently recording the visual display 137, for example a camera 139, may be utilized for permanent recordation of the positioning, orientation, and configuration of the object obstructing the wellbore.

Referring to FIG. 2, a segment of the acoustic transceiver comprising numerous piezoelectric crystals is depicted. FIG. 2 further depicts the orientation of the piezoelectric crystals 202 within the segmented acoustic transceiver 201. FIG. 3 depicts isolated anisotropic transceiver segment in which an electromechanical insulator 301 is shown encompassing the piezoelectric element 302 such that each of the segments are isolated from the entire mass of the segmented acoustic transceiver, so that they may be pulsed in unison, but receive energy separately as reflected from the fish, such that an adequate orientation and configuration of the fish may be depicted.

In operation, all transceiver segments are equally pulsed to provide a uniform output. The segments are then scanned individually to monitor the sonic energy reflected from the wellbore obstruction. The sequence and time delay in output pulses and scanning are received as reflected energy which is controlled through the transducer and gate trigger assembly as depicted in FIG. 1 in conjunction with the frequency and pulse generation apparatus. As the separate transceiver segments are scanned, the reception is relayed to the surface and displayed according to geometrical order, on a variable intensity oscilloscope or other display means with a high retention cathode ray tube. The amplitude of the reflected energy thus monitored may be indicated by the intensity of the cathode ray tube display, giving depth perception. The orientation of the obstruction in the hole is indicated by the North marker provided by the output of the flux-gate magnetometer for orientation of the tool in the wellbore. The forward looking sonic wellbore inspector may be centered in the wellbore by a bowstring centralizer as depicted in FIG. 1, or by various and sundry other means for positioning wellbore sondes and instruments within wellbores.

Various advantages inherent in the device disclosed herein become obvious through the discussion presented. The apparatus provides a wire line tool which does not require tripping of pipe or tubing. The configuration of obstructive debris in wellbores is immediately observable at the surface without having to trip the pipe. The tool is not run blind and readily shows its orientation at all times while running within a wellbore. The tool may be utilized in monitoring and guiding retrieving operations by running inside the fishing string to actually observe contact being made with the fish. The tool may also be utilized to observe bit cutting patterns made during actual drilling conditions, an aspect of interest in drilling research. Also, the placement and condition of downhole tools, for example packers, etc,, may be observed, a capability of interest to operations.

While the invention has been described above with respect to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as set forth herein.

Therefore, we claim:

1. A forward looking wire line sonic wellbore inspector, which comprises:

a. a housing;

b. a segmented piezoelectric crystal transceiver positioned in the lower portion of the housing;

0. a frequency generator;

d. a pulse generator receiving the frequency generation;

e. a transducer segment scanner electrically connected to the piezoelectric crystals and receiving the pulsed frequency generated;

f. a gate trigger controlling the sequence at which the piezoelectric crystals receive the pulsed frequency generated; and

g. means for receiving and interpreting the reflected acoustic energy from the piezoelectric crystals.

2. The apparatus of claim 1 further comprising:

a. means for determining the orientation of the housing in the wellbore; and

b. means for determining the depth of the housing in the wellbore.

3. The apparatus of claim 2 further comprising means for visually displaying the difference between the imparted energy and reflected seismic energy received by the piezoelectric crystals in their correct orientation.

4. The apparatus of claim 3 in which the means for receiving and interpreting the reflected seismic energy from the piezoelectric crystals comprise:

a. the transducer segment scanner of claim 3 receiving the reflected seismic energy from the piezoelectric crystals;

b. a first amplifier receiving the reflected seismic energy and pulsed frequency generated from the gate trigger; and

c. a counter-detector receiving the amplified reflected seismic energy and pulsed frequency generated so as to filter and determine the difference between the pulsed frequency generated and reflected seismic energy and generate a signal thereof.

5. The apparatus of claim 4 in which the means for determining the orientation of the housing in wellbore comprise:

a. a flux-gate magnetometer positioned in the upper portion of the housing; and

b. an orientation pulse generator-receiver, generating and receiving signals from the flux-gate magnet0m eter.

6. The apparatus of claim 5 in which the means for determining the depth of the housing in the wellbore comprises a wire line depth recorder connected at the surface to the wire line of the inspector.

7. The apparatus of claim 6 in which the means for visually displaying the difference between the imparted energy and reflected seismic energy received by the piezoeleectric crystals in the correct orientation comprise:

a. a second amplifier receiving the signal from the counter-detector;

b. a transducer scanner receiving the signal from the counter-detector;

c. an azimuth marker receiving the received signal from the orientation pulse generator-receiver; and

d. an oscilloscope receiving signals from the second amplifier transducer scanner and azimuth marker.

8. The apparatus of claim 7 further comprising means for centrailizing the apparatus in the wellbore. 

1. A forward looking wire line sonic wellbore inspector, which comprises: a. a housing; b. a segmented piezoelectric crystal transceiver positioned in the lower portion of the housing; c. a frequency generator; d. a pulse generator receiving the frequency generation; e. a transducer segment scanner electrically connected to the piezoelectric crystals and receiving the pulsed frequency generated; f. a gate trigger controlling the sequEnce at which the piezoelectric crystals receive the pulsed frequency generated; and g. means for receiving and interpreting the reflected acoustic energy from the piezoelectric crystals.
 2. The apparatus of claim 1 further comprising: a. means for determining the orientation of the housing in the wellbore; and b. means for determining the depth of the housing in the wellbore.
 3. The apparatus of claim 2 further comprising means for visually displaying the difference between the imparted energy and reflected seismic energy received by the piezoelectric crystals in their correct orientation.
 4. The apparatus of claim 3 in which the means for receiving and interpreting the reflected seismic energy from the piezoelectric crystals comprise: a. the transducer segment scanner of claim 3 receiving the reflected seismic energy from the piezoelectric crystals; b. a first amplifier receiving the reflected seismic energy and pulsed frequency generated from the gate trigger; and c. a counter-detector receiving the amplified reflected seismic energy and pulsed frequency generated so as to filter and determine the difference between the pulsed frequency generated and reflected seismic energy and generate a signal thereof.
 5. The apparatus of claim 4 in which the means for determining the orientation of the housing in wellbore comprise: a. a flux-gate magnetometer positioned in the upper portion of the housing; and b. an orientation pulse generator-receiver, generating and receiving signals from the flux-gate magnetometer.
 6. The apparatus of claim 5 in which the means for determining the depth of the housing in the wellbore comprises a wire line depth recorder connected at the surface to the wire line of the inspector.
 7. The apparatus of claim 6 in which the means for visually displaying the difference between the imparted energy and reflected seismic energy received by the piezoeleectric crystals in the correct orientation comprise: a. a second amplifier receiving the signal from the counter-detector; b. a transducer scanner receiving the signal from the counter-detector; c. an azimuth marker receiving the received signal from the orientation pulse generator-receiver; and d. an oscilloscope receiving signals from the second amplifier transducer scanner and azimuth marker.
 8. The apparatus of claim 7 further comprising means for centrailizing the apparatus in the wellbore. 